Multifrequency tuning system for radio receivers



April 26, 1938f w. CARPENTER MULTIFREQUENCY TUNING SYSTEM FOR RADIO RECEIVERS Filed Dec.

16, 1935 2 Sheets-Sheet l QN mm April 26, 1938. w. 1. CARPENTER MULTIFREQUENCY TUNING SYSTEM FOR RADIO RECEIVERS Filed Dec. 16, 1935 2 Sheets-Sheet 2 ii LL mammal m WA I v j Patented Apr. 26, 1938 UNITED STATES PATENT OFFICE MULTIFREQUENCY TUNING SYSTEM FOR RADIO RECEIVERS 2 Claims.

This invention relates to a multi-frequency tuning system for radio receivers.

The invention aims to provide, in a manner as hereinafter set forth, a multi-frequency tuning 5 system providing for a more practical usage of a tuning condenser than has been customary in standard practice in that the tuning condenser tunes one band of frequencies from maximum to minimum capacity or vice versa and with a continual rotation of the rotor of the condenser in the same direction cuts out the aforesaid frequency band and cuts in another entirely different band of frequencies from minimum to maximum capacity or vice versa; or in other 15 words, successive different bands of frequencies are tuned in and cut out on the rotation of the rotor of the condenser in the same direction in inverse order of frequencies of the respective bands. I Further objects of the invention are to provide, in a manner as hereinafter set forth, a multi-frequency tuning system which is comparatively simple in its construction and arrangement, strong, durable, thoroughly efiicient in its use, conveniently adjusted, accurate in action, readily assembled, and comparatively inexpensive to set up.

With the foregoing and other objects in view, the invention consists of the novel construction, 30 combination and arrangement of parts as will be more specifically referred to and as are illustrated in the accompanying drawings, but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the invention as claimed.

In the drawings:

Figure 1 is a vertical sectional view of an apparatus to provide a multi-frequency tuning system in accordance with this invention,

40 Figure 2 is an end View of the switching mechanism of the apparatus, and

Figure 3 is a diagrammatic view of the preselector, detector, oscillatory circuit employed.

With reference to the drawings, the front of the cabinet or housing of a radio receiving set is indicated at 20 and it is formed with superposed openings 2|, 22 having their axes aligning. The opening 2| is arranged above and is of materially greater diameter than the opening 22. The wall of opening 21 gradually decreases in diameter from its outer to its inner end. Extending through the opening 2|, as well as snugly engaging the wall of the latter, is a rectangular escutcheon member 23 open at its front and rear. 55 The member 23 includes a front endless flange 24 positioned against the outer face of the front 20, as well as being rigidly secured to the latter by the holdfast means 25. Fixed to and within the member 23 at its inner end is a vertical indicator or finder 26, in the form of a thin wire 5 disposed at the lengthwise center of member 23.

Positioned against the inner face of the front 26 is a vertically disposed bracket 21 provided near its lower end with a rearwardly extending angle-shaped arm 28 having a horizontal part 29 and a vertically disposed part 39 integral with and extending upwardly at right angles with respect to the rear end of the part 29. The body of the bracket 21 between its transverse median and lower end is formed with an opening 3% which aligns with the opening 32 provided in the part 30. The opening 31 registers with the opening 22. The body of the bracket 21 at its upper end is enlarged, as at 33, and formed with an opening 34.

A tuning knob arranged forwardly of the front 20 is indicated at 35, fixed to the outer end of a rearwardly extending rotatable short shaft 36 journaled in the openings 22, 3 l, and 32. Fixedly secured to the shaft 36 is a groove pulley 3'] arranged between the body of the bracket 21 and the part of the arm 28. Engaging in and operated from the pulley 31 is a power trans mitting pulley 38 of greater diameter than the pulley 31 and formed with a hub 39. Arranged 30 rearwardly of the bracket 21 and member 23 is a translucent dial structure 49 fixedly secured in spaced relation to the pulley 38 by the holdfast means 46. Within the cabinet or housing of the receiving set is a floor board 48 to which is secured an upstanding supporting structure, indicated at 49, 58 for a condenser structure 225 having its shaft indicated at 226. The structure 225 includes gangs of rotors 28l, 282 and 283 having their associated gangs of stators in- 40 dicated at 284, 285 and 286 respectively. The gangs of rotors are carried by shaft 226. Conducting blocks are designated 288, 289, 290 and to which the stators 284, 285, 286 respectively are secured. Circuit wire connections 29!, 292, 293 are provided for the blocks 288, 288, 290 respectively.

The shaft 226 has fixed to its rear end the hub 226 of a controlling cam 22'! formed with a segmental edge part 228 merging at one end into one end of a concave edge part 229, the other end of the latter merging into one end of a convex edge part 230, and a concave edge part 23! merging at one end into the other end of part 228 and at its other end into part 238. The edge part 230 is of less length than the edge parts 229, 23!. The edge part 228 is of materially greater length than any of the other edge parts. The purpose of the cam 221 will be presently referred to.

There is associated with the condenser structure 225 a plural switching structure generally indicated at 232 and it includes an upstanding plate 233 formed with an opening 234 for the passage of shaft 225. The plate 233 is formed with four radially disposed stems 235, 236, 231, 233 disposed at right angles to each other. The stem 235 at its outer end and at one side is formed.

with a rearwardly extending arm 239 disposed at right angles thereto. The stem 236 at its outer end and at one side is formed with a rearwardly extending arm 246 disposed at right angles thereto. The stem 231 at its outer end and at one side is formed with a rearwardlyextending .arm 24! disposed at right angles thereto. The stem 238 at its outer end and at one side is formed with a rearwardly extending arm 242 disposed at right angles thereto. The arms 235, 24! are arranged one above the other and in non-alignment and disposed on their lower lengthwise edges. The arm 246 is arranged below the arm 242 and disposed flatwise. The arm 24! is disposed in lateral relation with respect to the arm 239. The lengthwise edges of the arms 246, 242 are disposed at right angles with respect to the lengthwise edges of the arms 236, 24!. Arranged in parallel spaced relation relative to the arm 236 and depending relative to the latter is a rectangular plate 243 of insulation of materially greater length than the length of arm 239. The plate 243 is disposed on its lower lengthwise edge. Arranged above and in spaced relation to arm 24!], as well as extending inwardly therefrom, is a horizontally disposed rectangular plate 244 of insulation of materially greater length than the length of arm 246. Opposing in parallel spaced relation the front face of arm 24! is a rectangular plate 245 of insulation disposed on its lower lengthwise edge and of materially greater length than the length of arm 24!. Arranged below the arm 242 and extending inwardly therefrom, as well as being spaced from the lower face of arm 242, is a horizontally disposed plate 246 of insulation of materially greater length than the length of arm 242. The bottom edge of plate 243 is arranged in parallel spaced relation with the top edge of plate 245. The inner side edges of the plates 244, 246 are arranged in parallel spaced relation. The forward ends of the plates 243, 244, 245, and 246 are arranged in close proximity to the stems 235, 236, 231, 233, respectively. The plate 243 is secured to and arranged in spaced relation relative to arm 235 by the combined spacing and holdfast means 241. The plate 244 is maintained in spaced relation relative to and anchored with the arm 246 by a combined spacing and holdfast means 246. The plate 245 is secured to and maintained in spaced relation relative to arm 24! by the combined spacing and holdfast means 249. The plate 246 is maintained in spaced relation relative to and anchored to the arm 242 by the combined spacing and holdfast means 256. The said several holdfast means extend through the said several plates and arms as well as project from the said several arms.

The plate 243 in proximity to its lower edge has anchored thereto transversely thereof spaced independent contacts 25!, six in number, and to each of which is electrically connected a circuit connection 252. The active ends of the contacts 25! extend laterally and rearwardly from the plate 243. The plate 244 in proximity to its lower edge has anchored thereto transversely thereof spaced independent contacts 253, six in number, and to each of which is electrically connected a circuit connection 254. The active ends of the contacts 253 extend upwardly from the plate 244. The plate 245 in proximity to its upper edge has anchored thereto transversely thereof spaced independent contacts 255, six in number, to each of which is electrically connected a circuit connection 256. The active ends of the contacts 255 extend forwardly from the plate 245. The plate 246 in proximity to its inner edge has anchored thereto transversely thereof spaced independent contacts 251, six in number, and to each' of which is electrically connected a circuit connection 258. The active ends of the contacts 251 extend downwardly from the plate 246. The contacts 25!, 253, 255 and 251 at their active ends are split.

Secured to the arm 236 adjacent its forward side by the combined spacing and holdfast means 241 is an angle-shaped carrier 259. Secured to the arm 246 by the combined spacing and holdfast means 248 and adjacent the lower face of said arm is an angle-shaped carrier 256. Secured to the arm 24? by the combined spacing and holdfast means 249 and adjacent the rear face of the arm 24! is an angle-shaped carrier 26!. Secured to the arm 242 by the combined spacing and holdfast means 256 and adjacent its upper face is an angle-shaped carrier 262. Each carrier, with reference to Figure 2, includes an arm 253 and an arm 264 disposed at right angles to the arm 263. The arms 264 of the carriers are resilient. The arm 264 of the carrier 259 depends from and is curved outwardly relative to arm 239. The arm 264 of the carrier 266 depends inwardly relative to arm 246 and is curved. The arm 264 of the carrier 26! extends upwardly upon an outward curve relative to the arm 24!. The arm 264 of the carrier 262 extends inwardly upon an upcurve relative to the arm 242.

The arm 264 of the carrier 259 extends into the upper side of a rectangular block 265 of insulation and provides a resilient suspension for the latter. The block 255 has secured thereto a series of spaced independent adjustable circuit closing members 266 and six in number. To each circuit closing member 266 is attached a circuit connection 261. The members 266 coact With the contacts 253 for closing the circuits associated therewith. The carrier 259 normally tends to shift the members 266 to engage the contacts 253. The members 266 extend inwardly at an inclination with respect to the block 265. The arm 264 of the carrier 26!] extends into the upper side of a rectangular block 268 of insulation and provides a resilient suspension for the latter. The block 268 has secured thereto a series of spaced independent adjustable circuit closing members 269, six in number. To each circuit closing member 269 is attached a circuit connection 216. The members 269 coact with the contacts 255 for closing the circuits associated therewith. The carrier 266 normally tends to shift the members 269 to engage the contacts 255. The members 26!! extend upwardly at an inclination with respect to the block 268. The arm 264 of the carrier 26! extends into the lower side of a rectangular block 21! of insulation and provides a resilient suspension for the latter. The block 21! has secured thereto a series of spaced independent adjustable circuit closing members 212, six in number. To each circuit closing member 212 is attached a circuit connection 213. The members 212 coact with the contacts 251 for closing the circuits associated therewith. The carrier 26| normally tends to shift the members 212 to engage the contacts 251. The members 212 extend inwardly at an upward inclination with respect to the block 21 I. The arm 264 of the carrier 262 extends into the lower side of a rectangular block 214 of insulation and provides a resilient suspension for the latter. The block 214 has secured thereto a series of spaced independent adjustable circuit closing members 215, six in number. To each circuit closing member 215 is attached a circuit connection 216. The members 215 coact with the contacts l for closing the circuits associated therewith. The carrier 262 normally tends to shift the members 215 to engage the contacts 251. The members 215 extend downwardly at an in clination with respect to the block 214. The circuit closing members are adapted to engage in the split active ends of the contacts for closing the circuits.

The blocks 265, 214 are arranged at opposite inclinations. The block 265 extends below the block 214. The latter extends above the block 25 265. The inclinations of the blocks 265, 214 are downward and outward. The blocks 268, 211 are disposed at opposite inclinations. Block 268 depends below the block 21!. The latter extends above the block 268. The blocks 268, 21I extend upwardly at outward inclinations. The blocks 265, 268, 2H, and 214 have extending inwardly therefrom abutment members 211, 218, 219, and 280 which ride against the edge portion 228 of the cam 221. Holdfast means 28l are employed for connecting the carriers and abutment members to the blocks 265, 268, 211, and 214. The said abutment members 211 to 280 act to arrest the shifting of the blocks 265, 268, 211, and 214 by the carriers towards the edge portions of the cam whereby the high edge portion 228 of the cam 221, coacting with the said abutment members, will maintain circuit closing members clear of their contacts. The edge portions 229, 230 and 23I of the cam 221 constitute clearances and will permit the blocks 265, 268, 211, and 214 to extend inwardly to an extent whereby the circuit closing members may engage their associated contacts. The high edge portion 228 of the cam 221 coacts with the abutment members to move the circuit closing members clear of the contacts to open the circuits.

The edge portions of the cam 221, in connection with the abutment members 211 to 280, inclusive, will provide for the system to operate in a manner to be referred to.

5 The apparatus includes a dial illuminating means 303. Terminals 304, 305 form elements of the means 303. The latter is secured to an extension 306 formed on and centrally of the top edge of the front cheek 301 of the structure 225.

The illuminating means 303 is made active and inactive in a known manner.

The elements as shown and described, in connection with the circuit arrangement to be referred to will provide a multi-frequency tuning 5 system, including a tuning condenser having a stator and a rotor revoluble through a cycle of 360, a set of normally open tuning circuits common to a first range of frequencies, a set of normally open tuning circuits common to a second range of frequencies, a set of normally open tuning circuits common to a third range of frequencies, a set of normally open tuning circuits common to a fourth range of frequencies, each range of frequencies covering a portion of the spectrum 5 different from that covered by any one of the other ranges of frequencies, and a multiple switching assembly, the condenser and assembly having coacting means to respectively provide, on the revolving of the rotor for a part of its cycle in one direction to partly enmesh it with the stator for the closing of the circuits common to the first range for a period to tune the frequenices of the first range from a higher to a lower frequency; on a continuance of the revolving of the rotor in a like direction for another 'part of its cycle to complete the extent of the enmeshing thereof with the stator for opening the circuits common to the first range and the closing of the circuits common to the second range for a period to tune the second range from a higher to a lower frequency; on a continuance of the revolving of the rotor in a like direction for another part of its cycle to partially unmesh with the stator, for opening the circuits common to the second range and closing the circuits common to the third range for a period to tune the third range from a lower to a higher frequency; and on a continuance of the revolving of the rotor in a like direction for another part of its cycle to completely unmesh it from the stator, for opening the circuits of the third range and the closing of the circuits common to the fourth range for a period to tune the fourth range from a lower to a higher frequency.

With reference to Figure 3, there is illustrated a circuit arrangement 0 which is termed a preselector, detector, oscillator circuit covering four bands of frequencies.

An explanation relative to circuit 0 will be as follows: With reference to band one, for example, the switches B B and B are closed with tuning condensers C C and C completely unmeshed. With the aforesaid switches closed then tuning elements C D -L and C D -L and C D -L are made active in circuit and tune a band of frequencies as the tuning condensers C C and C are turned through 90 during which time the dial band scale turns only through 90. This represents the end of band one, and with the aforesaid tuning condensers partly enmeshed. Now as the aforesaid tuning condensers are turned further in the same direction, then switches B B and B open, throwing out of circuit C D -L and C D -L and C D -L and at the same time switches B B and B close with tuning condensers C C and C partly enmeshed. With the aforesaid switches closed, then tuning elements C D L and C D L and C D L are made active in circuit and tune a second band of frequencies different from band one frequencies as the tuning condensers C C and C are turned in the same direction through 90 during which time the dial band scale turns through a second range of 90. This point is the end of band two, and with the aforesaid tuning condensers fully meshed. Now as the aforesaid tuning condensers are turned further in the same direction, then switches B B and B open, throwing out of circuit tuning elements C D -L C D -L and C D -L and at the same time switches B B 13 close with tuning elements C C and C completely meshed. With the aforesaid switches closed, then tuning elements C D -L C D L and C D L are made active in circuit and tune a third band of frequencies different from bands one and two frequencies as the tuning condensers C C C are turned in the same direction through another 90 during which time the dial band scale turns through a third range of 90. This point is the :throwing out of circuit tuning end of band three, and with the aforesaid tuning condensers partly unmeshed. Now as the aforesaid tuning condensers are turned further in the same direction, then switches B B B open, elements C D L C D -L and C D --L and at the same time switches B". B and B close with tuning condensers C C and C partly unmeshed. With the aforesaid switches B B and B closed, then tuning elements C D -L C D L and C D -L are made active in circuit and tune a fourth band of frequencies different from bands one, two, and three frequencies as the tuning condensers C C and C are turned further in the same direction another during which time the dial band scale turns through a fourth range of 90", which marks the end of one complete turn of the tuning condensers C C and C and one complete turn of the dial band scale. Now as the aforesaid tuning condensers are turned further in the same direction, then switches B B and B open, throwing out of circuit tuning elements C D"L C D -L and C D L and at the same time switches B B and B close with tuning condensers C C and C fully unmeshed. With the aforesaid switches B B and B closed, then tuning elements C D -L C il -L and C D -L are made active again, which brings us back tothe starting point again of band one. It is to be noted that the coils are in inductive relation as follows: D with L D with L D with L D with L D with L D with L D with U, D with L D with L D with L D with L and D with L The system in accordance with this invention provides for the operator tuning two different bands of frequencies going into mesh and two when coming out of mesh. This gives a con denser double function, whereas it has been conventional to use single function. It saves equipment use. It saves time in tuning' It simplifies the tuning for the operator. It makes one-spot tuning possible on the dial, and eliminates the use of a number of visible dial scales over all and the associated double end pointers that are confusing to the operator as to where the dial is supposed to be read.

When the tuning condenser is full in mesh with a given coil inductance, the condenser is set at its highest capacity, but its lowest frequency range; and when the tuning condenser is out of mesh with the same given coil inductance as used aforesaid, the condenser is set at its lowest capacity, but its highest frequency range, whereby right after a switch action the follower band is tuned in the opposite direction as to frequency or capacity direction.

What I claim is:

1. In a multi-frequency tuning system, a tuning condenser including a stator and a rotor revoluble through a cycle of 360, a set of normally open tuning circuits common to a first range of frequencies, a set of normally open tuning circuits common to a second range of frequencies, a set of normally open tuning circuits common to a third range of frequencies, a set of normally open tuning circuits common to a fourth range of frequencies, each range of frequencies covering a portion of the spectrum different from that covered by any one of the other ranges of frequencies, and a multiple switching assembly, said condenser and assembly having enacting means to respectively provide, on the revolving of the rotor for a part of its cycle in one direction, to partly enmesh it with the stator for the closing of the circuits common to the first range for a period to tune the frequencies of the first range from a higher to a lower frequency; on a continuance of the revolving of the rotor in a like direction for another part of its cycle, to complete the extent of the enmeshing thereof with the stator for the opening of the circuits common to the first range and the closing of the circuits common to the second range for a period to tune the second range from a higher to a lower frequency; on a continuance of the revolving of the rotor in a like direction for another part of its cycle to partially unmesh with the stator, for opening the circuits common to the second range and closing the circuits common to the third range for a period to tune the third range from a lower to a higher frequency; and on a continuance of the revolving of the rotor in a like direction for another part of its cycle and to completely unmesh it from the stator, for opening of the circuits of the third range and the closing of the circuits common to the fourth range for a period to tune the fourth range from a lower to a higher frequency.

2. The invention as set forth in claim 1 having said switching assembly formed with a series of independent sets of contacts and a series of independent sets of circuit closers, each set of circuit closers for coaction with a set of contacts to close a set of tuning circuits, a set of contacts and the set of circuit closers coacting therewith being interposed in a set of tuning circuits, the circuit closers of each set thereof being adjustable.

WEBSTER I. CARPENTER. 

